| Project/Area Number |
09670304
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Bacteriology (including Mycology)
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| Research Institution | Tokushima Bunri University |
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Principal Investigator |
OKAMOTO Keinosuke Tokushima Bunri University・Faculty of Pharmaceutical Sciences, Professor, 薬学部, 教授 (70131183)
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| Co-Investigator(Kenkyū-buntansha) |
YAMANAKA Hiroyasu Tokushima Bunri University・Faculty of Pharmaceutical Sciences, Associate Profess, 薬学部, 助教授 (30202386)
FUJII Yoshio Tokushima Bunri University・Institute of Pharmacognosy, Associate Professor, 生薬研究所, 助教授 (60122587)
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| Project Period (FY) |
1997 – 1998
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| Project Status |
Completed (Fiscal Year 1998)
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| Budget Amount *help |
¥3,200,000 (Direct Cost: ¥3,200,000)
Fiscal Year 1998: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1997: ¥2,600,000 (Direct Cost: ¥2,600,000)
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| Keywords | Escherichia coli / Diarrhea / Toxin / Membrane / Disulfide bond / Gene manipulation / 膜 / ジスルフィド精合 / ジスルフィド結合 |
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| Research Abstract |
It has been reported that enterotoxigenic Escherichia ccli produces tow kinds of heatstable enteotoxin, STI and STII.These STs produced in cytoplasm are efficiently secreted into milieu and these extracellular STs induce diarrhea in host. The STs in cytoplasm are the immature toxins which can not induce diarrhea in host. However, these STs secreted into milieu are mature toxin which can. In this study, we investigated how these inactive STs are converted into their active form and how these active STs are secreted into milieu. We obtained the following results.
1. Both STI and STII possess intamoleculatr disulfide bonds which are essential for expression of their activities. The study about the mode of disulfide bond formation revealed that DsbA, a periplasmic enzyme, catalyzes the formation of the bonds in both STI and STII.And the study about the mechanism of secretion of STs revealed that the disulfide bond formation is absolutely required for STII to pass through the outer membrane, but the formation is not necessary for STI to pass through the outer membrane. Furthermore, our study showed that the glutamic acid at position 7 of STI is involved in the reaction of STI with DsbA
2. It has been shown that TolC, an outer membrane protein, is involved in the secretion not only of protein but also of small molecules such as antibiotics. To investigate whether TolC is involved in the secretion of STI, we prepared the tolC-mutant strain and examined the secretion of STI from the mutant strain. The result showed that TolC is directly involved in the secretion of STI.And we confirmed that the involvement of ToIC in the secretion of STII using our system.
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